Sleep is a fundamental index of behavioral disturbance and recent reviews of drug withdrawal concluded that sleep disturbance is common to withdrawal from virtually all drugs of dependence. Nevertheless, the effects of drug withdrawal on sleep have received little research attention. There is evidence that objective sleep measures may more sensitively index the effects of nicotine withdrawal and nicotine replacement than do traditional self-report measures. Moreover, the consequences of sleep disturbance such as negative affect and cognitive impairment resemble those of nicotine withdrawal. Thus, sleep disturbance may not only index nicotine withdrawal, but may be a mechanism that causes or exacerbates other withdrawal symptoms. The study of nicotine withdrawal is important because withdrawal;l causes clinically significant dysphoria, impairs cognitive and psychomotor performance; discourages quit attempts; and, is a useful model for studying drug dependence. Nicotine, withdrawal may also contribute to relapse and an inability to quit smoking, although this relationship p has not been consistently demonstrated. Nevertheless, key mechanisms through which nicotine deprivation affects behavior remain to be identified. The specific aims of this research are to; 1. Characterize the effects of nicotine withdrawal on sleep among women using comprehensive polysomnographic recording. 2. Assess the effects of a history of depression on objective sleep parameters during withdrawal. 3. Examine objective sleep parameters as indices of nicotine withdrawal or mechanisms that cause or exacerbate other withdrawal symptoms. This research will yield unique data regarding the role of sleep in nicotine withdrawal in two groups of female smokers - those with a positive history of depression (n=6) and those with a negative history of depression (n=6). Evidence suggests that women may experience more severe withdrawal than men and our research suggests that the effects of withdrawal on polysomnographic sleep measures may be greater in women than men. The effects of a history of depression of nicotine withdrawal among women ar of particular interest because; the prevalence of a history of depression may be extremely high among female smokers; the magnitude of withdrawal severity may be significantly elevated in these smokers; and, they may be especially likely to demonstrate relations between objective sleep parameters and other nicotine withdrawal symptoms (e.g. postcessation negative affect). Participants will undergo two precessation nocturnal polysomnographic assessments of sleep and three postcessation assessments. Nocturnal polysomnography provides accurate quantitative assessment of sleep.